The element also called C / 2014 UN271 is about ten times larger and has a mass 1,000 times greater than that of the average comet. Scientists thus estimated that its diameter was between 100 and 200 kilometers. Specialists have struggled to make precise assessments because it is still extremely far from Earth.
Visible with very powerful instruments
To calculate its size, astronomers had to rely on the amount of sunlight it reflects. The object should however approach our planet and be closest to it in 2031. It will nevertheless remain at a distance of 11 astronomical units from the Blue Planet, or approximately 1.65 billion kilometers. Even as close as possible to the Earth, the comet will therefore only be visible with particularly powerful instruments.
In addition to its size and trajectory, C / 2014 UN271 stands out from other celestial elements by the rarity of its appearances in our internal solar system. Its last passage dates back to three million years ago, that is to say at the time when our planet was, among other things, populated by Australopithecines. The comet was born in the Oort cloud, to 40,000 astronomical units from the sun.
Never had a body come from so far away been spotted heading towards Earth. Scientists hope to learn a lot from the study of this celestial object, especially when it comes to the formation of massive celestial bodies and the movements of the planets.
Mars is known for its thin atmosphere, where CO₂ dominates and provides most of the atmospheric mass and pressure, the latter comparable to that found in the Earth’s stratosphere more than 30 kilometers above. from the surface.
But what about water? Water on Mars is currently seen on the surface as a layer of ice at the North Pole several kilometers thick, as seasonal frost at colder times of the year, and in the atmosphere, in the form of vapor and ice in the clouds. Nevertheless, the Martian atmosphere is extremely dry compared to the Earth: in proportion, 100 times less water is present in the atmosphere of Mars than in that of the Earth. While precipitation on Earth results in water films of several centimeters, the water that would be precipitated on Mars would only form a thin film less than a millimeter.
From new data to better understand why there is (almost) of water on Mars when it had to be abundant in the past.
Water escapes from the Martian atmosphere
Because everything indicates that Mars was not always the cold and arid planet we know today. Mars exhibits many testimonies on its surface of a distant past – about four billion years ago, where liquid water circulated in great streams and stagnated in the form of basins or lakes, such as in the Jezero crater as the rover Perseverance is exploring for traces of past life.
In order for liquid water to circulate as much and to reside on the surface long enough to make all these imprints, it is necessary to invoke a climate radically different from the one we observe today. Mars, Earth and Venus were arguably accreted from the same basic materials, which means they must have known great similarities very early in their history. But while the Earth and Venus have retained most of their thick atmosphere, Mars, due to its small size and low gravity, has not been able to retain its atmosphere over time.
It is indeed this “ escape theory ” that explains the current thinness of Mars’ atmosphere. This escape occurs very high in the atmosphere, above 200 kilometers, where the molecules have already dissociated into atoms and where the lighter ones, like hydrogen, can tear themselves away from the weak gravity of Mars. Exposed to the energetic particles of the solar wind, this “ exosphere ” of Mars is also its “Achilles heel”, because over time it has allowed the equivalent of hundreds of current atmospheres to be lost in space.
This escape was known to all, especially because Martian water has a composition that is unique to it. Indeed, the isotopes of water, in particular “semi-heavy” water HDO where a hydrogen atom (H) is replaced by a deuterium atom (D) twice as heavy, which one has. measured on Mars since the 80s, reveal a relative concentration 6 times greater in deuterium on Mars than on Earth. This relative enrichment is interpreted precisely as the result of the escape of hydrogen, which gradually left behind the heaviest isotopes, in this case D and HDO, explaining this enrichment ratio of 6.
By extrapolation, the initial quantity of water on Mars must have been at least 6 times greater than now, or the equivalent of a liquid layer of a hundred meters covering the planet. This shows to what extent the HDO / H20 ratio is crucial for projecting oneself into the youth of Mars and for shedding light on the hypothesis of a past hot and humid climate, prior to its habitability.
These results from the Trace Gas Orbiter allow us to better understand the conditions under which water and semi-heavy water present in the lower atmosphere are transported to the very upper atmosphere and then transform into atoms capable of escaping. Indeed, we have long wondered to what extent intermediate processes can modify the way in which hydrogen and deuterium from water access the exosphere. For twenty years, two theories have suggested that hydrogen and deuterium cannot reach the exosphere in the proportions that are theirs in the water molecules of the lower atmosphere. These intermediate processes are on the one hand condensation, which forms the clouds of Martian water ice, and on the other hand photolysis., which breaks the water molecule and releases a hydrogen or deuterium atom under the action of UV rays.
Studied in the laboratory for decades, condensation and photolysis are known to affect water and its isotopes in a specific way: this is called “isotopic fractionation”. It is also thanks to our understanding of isotopic fractionation that it is possible to trace the past climatic course of the Earth by drilling ice cores at the poles, where the concentration of HDO reveals the more or less cold climate that reigned. when the water has condensed into ice. It is a discipline where the French community excels , and which has made it possible to initiate exploratory work in the Martian context within French laboratories.
On Mars, fractionation by photolysis operates in an opposite way to fractionation by condensation. Above all, the two do not operate at the same time in the course of water – this last point has a major impact on the fate of the hydrogen and deuterium atoms. In fact, the condensation of water vapor tends to concentrate the HDO in the ice formed, and thus de facto de facto depletes the vapor in HDO. Photolysis, for its part, tends to promote the release of deuterium present in the HDO molecule. For a long time, it was assumed that isotopic fractionation by condensation, which makes the vapor poorer in deuterium, dominated photolysis and forced the proportion of deuterium in the exosphere to be lower than in water in the lower atmosphere.
What the recent study reveals is that condensation actually plays a minor role in the proportion of deuterium in the exosphere. Thanks to the Atmospheric Chemistry Suite instrument of the Trace Gas Orbiter and its simultaneous measurements of H20 and HDO, we were able to show where the hydrogen and deuterium atoms come from, at an altitude and a period of the Martian year. where condensation does not have the possibility of interfering with photolysis.
It is indeed photolysis which produces most of the atoms and which dictates the isotopic fractionation of the hydrogen atoms which escape from the upper Martian atmosphere.
Next destination: understanding the path of water, from the surface to the upper atmosphere
This questioning of our understanding of the processes that lead to the escape of water poses a critical milestone in attempts to trace the history of water on Mars. Only the Trace Gas Orbiter satellite is capable of revealing the joint concentrations of H20 and HDO. But another satellite, this time from NASA, MAVEN , is able to observe and characterize the hydrogen and deuterium populations in the exosphere.
Since its inception, the Fast and Furious franchise has continued to push the boundaries of its adventures . After having done incredible rodeos in the streets as on the racetracks, the heroes are now preparing to go to space. And as crazy as it sounds, space travel fits into the equation as well. Thus, Pearce and Parker will leave the face of the earth, towards the cosmos. If we do not yet know the reason for such a trip, we can still discover the machine that will take them there.
It is therefore aboard a Pontiac Fiero that our protagonists are preparing to experience this extraordinary journey. With its built-in rocket motor, the car can now leave dry land. The car thus becomes the first to go beyond the sky, showing itself to be even more efficient than a traditional airplane.
A rocket car for Fast and Furious 9
We owe this beautiful exclusivity to TikToker Daniel Mac. The latter went to the set of the new shutter to spend time with actor Tyrese Gibson. The latter took the opportunity to present him a preview of the incredible car in question. But the visit will have been short-lived. Indeed, Gibson alerted the influencer to the potential dangers of the vapors emanating from the engine. But the actor mostly played the humor card, offering his visitor a golf cart as a farewell gift.
The influencer did not stop there. The latter was also able to share some time with Sung Kang, finally back in the franchise. The actor took the opportunity to show off his racing car, a Toyota Supra . Even if the latter was not designed to go into space, it is nonetheless impressive.
Expected the next few days in theaters, Fast and Furious 9 promises a new version doped with special effects and incredible action scenes. Not to mention the upcoming release of the second episode of Hobbs & Shaw , which may also wreak havoc!
Disappointment! While Psyche 16 could make every inhabitant of planet Earth a billionaire, a recent study on this most expensive asteroid in the galaxy casts doubt …
Undoubtedly the ancient nucleus of a dead planet, the asteroid Psyche 16, discovered in 1854 (!), Has fed all fantasies for decades.
It is because the profusion of metals (nickel, iron, gold …) that make up this enormous asteroid could make … every inhabitant of planet Earth a billionaire. By itself, the celestial object « weighs » 700 quintillions of dollars (700 billion billion dollars …).null
Suffice to say that the sending of a NASA probe scheduled for 2022 (arrival scheduled for 2026) is fraught with challenges.
94% less metallic than expected
But now, a new study published in the Planetery Science Journal comes to shake up the certainties. Psyche 16 would in fact be a heap of rubble less « metallic than expected by about 94% » and with « 35% vacuum ».
These « more recent telescopic observations suggest the additional presence of pyroxene (material present in eruptive rocks) with a low iron content and exogenous carbonaceous chondrites (iron present in oxidized form) on the asteroid’s surface. »
According to the authors of the study, « Psyche is composed at best of 82.5% metal, 7% low-Fe pyroxene and 10.5% carbonaceous chondrite by weight. »
On reading this study, we understand that the virtual fortune of each inhabitant of our planet therefore seems to have evaporated. NASA’s mission will therefore be particularly monitored from 2022.
The wealthy businessman, boss of Amazon, announced on Monday that he would participate in the 1st space tourism trip organized by his own company, Blue Origin
It’s official ! The American Jeff Bezos, wealthy boss of Amazon, revealed on Monday that he would participate in the first space tourist trip organized by his company Blue Origin, created with the aim of lowering the costs of access to space in 2000 Accompanied by his brother Mark and the winner of an auction, he will set off in the space aboard the New Shepard capsule.
“Since I was five years old, I have dreamed of traveling in space. On July 20, I will be making this trip with my brother. The greatest adventure, with my best friend, ”wrote the billionaire in a post on his Instagram account.
If on the Red Planet NASA takes center stage with the exploits of its helicopter, China should soon steal the show. In two or three weeks, or even a few days, the Zhurong rover is expected to land on Mars. He is currently aboard the Tianwen-1 probe, which is working to locate the best place to land it.
While all eyes are on the ongoing Perseverance mission and NASA’s Ingenuity helicopter , let’s not forget that China is preparing to land on the Red Planet. In orbit since February 10 around the planet, the Chinese probe Tianwen-1 is preparing the landing of the Zhurong rover on a date that has not yet been made public but which is believed to be between mid-May and early June. If all goes according to plan, China would become the second country, after the United States, to land a rover on Mars. Note that the former USSR did succeed in landing a rover on the Red Planet in 1971, but the latter only operated for a few tens of seconds (March 3).
In order for the Zhurong rover to land safely in the southern part of Utopia Planitia , a detailed analysis of its landing site is required. Indeed, you should know that the Chinese Space Agency, unlike NASA or ESA , does not have a high resolution map of the planet Mars. Thus, NASA’s MRO orbit (and its Hirise camera) was able to provide very detailed maps, only a few tens of centimeters in resolution, of the Perseverance landing site .well before its launch. The Tianwen-1 probe is currently mapping the region to draw the most detailed maps possible. The goal is to locate the most suitable place to land the rover safely in an environment not too crowded with large rocks and as flat as possible.
An ambitious rover
The approximately 250- kilogram rover is larger than NASA’s Spirit and Opportunity rovers but about a quarter the size of Curiosity and Perseverance. Equipped with six motorized wheels that will allow it to move like a crab, Zhurong will be able to travel up to 200 meters per hour. It carries six instruments, including a laser camera very similar to the ChemCam instrument of the American rover Curiosity. Added to this are optical cameras, a radar to probe the subsoil, a spectrometer , a magnetometer and a meteorological station (measurements of temperature, pressure and windespecially). Its four solar panels will produce the energy necessary for its operation, which is expected to last more or less 90 days. The data will be relayed by the Tianwen-1 orbiter, or even the European Space Agency’s Mars Express probe if China so requests.
On the night of Monday April 26 to Tuesday April 27, the Moon will be closer to Earth than every other night of the year, making it appear larger than usual.
This phenomenon only occurs once or twice a year. But why do we speak of « super moon »? Will it be really pink? What do you need to know to make the most of it?
Why do we speak of a “super moon”?
This alignment of the Earth, the Moon and the Sun is an astrological phenomenon which owes its name of « Supermoon » in English (super-moon) to the American astrologer Richard Nolle who named it thus in 1979. Since the term remained, it is notably taken over by NASA.
In fact, the moon will appear larger to us than usual because it will be closer to the Earth . “The average distance between the Earth and the Moon is 384,000 km,” explains Gilles Dawidowicz, secretary general of the Société astronomique de France. The minimum distance of 356,000 km was reached in 2016, a record since 1948 and which will not happen again until 2034 ”.
The 2016 super moon was 30% brighter than usual. « There, it will be less exceptional but it is still a nice spectacle », warns the specialist.
With the naked eye, it’s quite difficult to see a difference in size between a full moon and a super moon. If we put two photos side by side, it would be like having a lime on one side and a lemon on the other. Gilles Dawidowicz
Will it be really pink?
No the moon will not be pink
No need to look for the Moon in the hope of seeing it take on a pinkish hue today: it will not have changed color. The expression « pink moon » has no scientific value.
It is an imprint of a North American cultural tradition, probably stemming from the Amerindians. Moon names were applied each lunar month (not just the full moon day), starting with either a new moon or a full moon. Since the 1930s, these names attributed to the Moon have been used in The Old Farmer’s Almanac , an American periodical published since the 18th century, popular for its weather forecasts and cooking recipes. For the month of April, the almanac uses the nickname « Full Pink Moon » (which was inspired by the spring flowering of the plant Phlox subulata ).
NASA regularly uses these nicknames in its official communications, which may contribute to maintaining a certain confusion between this cultural tradition and scientific reality. On April 20, for example, the space agency headlined “ The Next Full Moon Is A Pink ‘Supermoon’ , ” referring to the April 27 Full Moon.
How to observe it well?
To be full of eyesight, it is better to watch for the sunset or the sunrise . The Earth’s atmosphere creates a magnifying effect on our vision of the Moon, ideal for taking pretty pictures.
And for a more precise observation, it is advisable to equip yourself with a telescope or a telescope, « a spectacle without danger », certifies Gilles Dawidowicz.
But for the latter, nothing beats an eclipse for total amazement. Note the date: the next lunar eclipse will take place on November 19, 2021.
It doesn’t just rain on Earth. Venus, Jupiter, Saturn or even Titan, Saturn’s largest satellite, also experience showers. What do they look like? Researchers at Harvard University in the United States modeled the drops of these extraterrestrial rains, and compared them to ours …
On Earth, it rains water. But on Venus, it tumbles sulfuric acid. The thick atmosphere of Jupiter is traversed by showers of helium or hailstones of ammonia and water mixed together. And on Titan, the largest satellite of Saturn, we can wipe a grain of liquid methane … With their atmospheres varied in composition, pressure, temperature, the planets of the solar system and their satellites offer sometimes very exotic rains. But what do the drops that carry them look like? According to a study conducted by researchers at Harvard University, and published in the Journal of Geophysical Research , they would ultimately be quite similar to ours
20 mm drops on Titan
To reach this conclusion, the American planetologists Kaitlyn Loftus and Robin Wordsworth modeled the formation of these drops according to the characteristics of the atmosphere and the gravitational pull of the planet. First observation: the more massive the star, the smaller the drops. This is understandable: for a drop to detach from the cloud where it forms, it must be sufficiently attracted by the gravitational field of the planet. However, the more massive a star, the more intense this field. Thus, a drop of methane on Titan (0.22 times the Earth’s mass) is twice as large (20 mm maximum) than on Earth, according to the researchers’ simulations. Severity is not the only criterion that matters. This work emphasizes that the size of the drops is also constrained by their fall. Too small, they evaporate before hitting the ground. Too big, they break into several smaller droplets. Applied to the Earth, this means that a drop measures between a tenth of a millimeter and 11 millimeters. This is why the Breton drizzle is so different from the stormy downpour …
The researchers also studied how drops composed only of water would fall on different planets in the solar system. By comparing with the Earth, Mars (when the climatic conditions were compatible with the presence of water), and the gas giants (Jupiter and Saturn), they found that the raindrops behaved in their fall (speed, shape of gout) in a similar way in these atmospheres which have nothing to do with it. As for their size, it would vary from 7 mm on Jupiter to 30 mm on Titan. This remains a modest difference given the difference between these stars. This relative homogeneity could be explained by the fact that the characteristics of the drops are more dependent on molecular interactions within the fluid than on external conditions.https://d-2223262752363715778.ampproject.net/2104022034000/frame.html
Sizes of water drops on different planets. Credits: AGU. Click on it to see in big
Rains of iron or diamonds
» This work is useful because it will make it possible to include rain and hail in the modeling of the atmospheric circulation of planets , comments for Sciences et Avenir Tristan Guillot, planetologist at the Observatory of the Côte d’Azur, at the origin of the theory of hailstones mixing water and ammonia on Jupiter. However, we saw with the space probe Juno that it is essential to understand the deep atmosphere of Jupiter, and by extension those of all the gas giant planets which do not have They are also valuable a few months before the launch of the James Webb Space Telescope (JWST), scheduled for the end of 2021, and which should observe many exoplanets, many of which are gas giants« By finely analyzing the light coming from these planets orbiting other stars, astrophysicists should be able to deduce the composition, but also the dynamics of their sometimes very exotic atmospheres. » For that, we will need the tools like these models developed by Harvard researchers « , concludes Tristan Guillot. When we consider that on certain exoplanets, it could rain iron, or diamonds, we are in fact eager for the JWST to turn to them.
It is good to be a billionaire in new technologies. Tuesday, Jeff Bezos potentially won $ 6 billion and Mark Zuckerberg 3.8 billion … But the prize goes to the boss of Tesla and SpaceX, who touched a jackpot of $ 25 billion.
The billionaires in new technologies lived, Tuesday, a rather enriching day … The vaccinations in the United States, the recovery plan in the country or the prospects of an economic recovery have indeed put them back in the saddle. technology stocks on Wall Street.
The Nasdaq, which brings together the main new technology companies in the United States, recovered in the space of a day more than 3.6%, while the trend was rather trending downwards since the beginning of the year . As a result, the potential fortune of the main billionaires has grown considerably.
Jeff Bezos, the boss of Amazon, won 6 billion dollars, Mark Zuckerberg 3.8 billion … But the big winner is Elon Musk . In one day, it touched almost the equivalent of the annual GDP of Iceland or Estonia – a trifle of $ 25.1 billion. According to Bloomberg, his wealth was valued at $ 149 billion at the start of the week, now to $ 174 billion.
A boost from Bitcoin
The boss of SpaceX has mainly benefited from a positive note from an analyst for his brand of electric cars Tesla. Unlike the others, the analyst estimated that the group can achieve earnings per share of $ 12 by 2023, nearly double the current consensus of industry experts.
This note woke up investors. Tesla shares climbed 20% during the day … Elon Musk also took advantage of the craze for the virtual currency Bitcoin, which exceeded the mark of 46,600 euros, and in which he invested nearly 1, $ 5 billion.
Elon Musk is also getting closer to Jeff Bezos to become the richest man on the planet again, a place he had occupied at the beginning of the year . According to Bloomberg, he is now only $ 6 billion from the founder of Amazon.
On social networks, some are spreading the rumor of Elon Musk’s death. If the rumor has been denied, it comes at a bad time for the boss of Tesla.
At the end of the day on Friday, a funny rumor appeared on social networks, under the hashtag #RIPElon. Some internet users have tried to pretend that Tesla’s boss was dead. Elon Musk has not officially responded. We would have imagined him repeating with humor the words of Mark Twain: “the rumors of my death are greatly exaggerated”. But it is likely that he was satisfied with a simple incredulous smiley on Friday March 5 to express his state of mind.
Elon Musk facing colossal losses
We don’t really know the why and how of this affair. But some US sites believe that individuals may have wanted to benefit economically. We have seen screenshots of fake titles circulating, for example blaming a Tesla battery. Another article questioned the “consequences for the financial markets” of the death of the boss of the automobile manufacturer. Another even tried to impersonate Tesla’s communications department… which had been dissolved by Elon Musk.
While the story may seem anecdotal, this story does not come at the best time for Elon Musk. At the weekend, billionaire Ron Baron sold Tesla stock for $ 1.8 million, causing its market value to plummet. However, since Elon Musk’s wealth is mainly linked to the price of his share, he has also dropped dramatically. According to Bloomberg’s ranking, he is now $ 20 billion behind Jeff Bezos, the boss of Amazon (177 versus 157 billion). In total, Tesla stock has lost 11% of its value over the past week. A drop in the bucket when we know that the stock jumped 743% in 2020, but it also illustrates the volatility of Tesla’s stock and the stock market in general. Elon Musk himself has been playing it in recent weeks,by promoting Dogecoin among others . There is no guarantee that the last few days will make him calm down. One thing’s for sure, he’s alive and well, as he proved by tweeting again over the weekend.null